This invention relates generally to laser scanning apparatus and more particularly to fix-mounted, e.g., counter type, laser scanning apparatus.
Various laser-based scanning systems have been disclosed in the patent literature and many are commercially available to read bar codes, e.g., the uniform product code, which is imprinted on packaging for product, or on the product itself, or on some other item.
One type of scanning system is referred to as a counter or xe2x80x9cslot scannerxe2x80x9d. Such devices are generally mounted within a housing in a checkout counter of a supermarket or other retail establishment, and include a window at the top thereof through which a scanning pattern is projected. The scanning pattern is created by a laser and associated optical components, e.g., mirrors, etc., which typically produce plural scan lines which are either parallel to one another and/or intersect one another. When an item bearing a bar code is brought into the field of the scan pattern so that the pattern traverses the bar code light is reflected off of the bar code and is received back through the window of the slot scanner, whereupon decoding means converts the received light into an electrical signal indicative of the bar code. These signals can then be utilized to identify the article bearing the code and provide pricing information.
In order to ensure that a bar code is traversed suffiiently so that it can be read accurately irrespective of its orientation within the scan pattern, prior art counter scanners have utilized various optical configurations including mirrors, prisms, and the like to fold the laser beam and create complex patterns. Examples of such patterns are comb patterns, orthogonal patterns, interlaced patterns, star-like patterns, etc. While such patterns may be suitable for their purposes, the means for creatig them has resulted in housings which were quite large in size.
In my U.S. Pat. No. 4,713,532 there is disclosed a counter or slot scanner producing an aggressive scanning pattern having at three rastered groups of intersecting scan lines to form a large xe2x80x9csweet spotxe2x80x9d to enable the bar code to be read omnidirectionally, i.e., irrespective of its orientation with respect to the scanner. That scanner is housed within a very compact, small footprint housing which is arranged to be mounted under a counter or disposed on a counter. Depending upon the orientation of the scanner, its window may be horizontal or at some other orientation, e.g., vertical. Devices embodying the teachings of that patent have been sold by the assignee of that patent (and of this application), Metrologic Instruments, Inc., under the designation MS260.
Metrologic Instruments, Inc. has also sold other compact counter or slot scanners under the designation MS360. Those scanners also produce a broad, aggressive scan pattern. In that case the pattern is made up of five rastered groups of intersecting scan lines.
While the aforementioned counter scanners have proved suitable for their intended purposes it has been determined that in certain applications the production of a broad scanning pattern is less than optimum. For example, in some check-out counter applications it is desirable to create a scanning pattern which, although aggressive, is confined within a relatively narrow volume, to prevent unintentional scanning of nearby objects. Hand-held scanners while providing for scanning within a confined volume (to prevent unintentional scanning), nevertheless suffer from various drawbacks, one of which being aggressiveness of the scanning pattern.
Thus, the need exists for a scanner device which combines the versatility of a hand-held scanner with the aggressiveness of a counter or slot scanner.
In many mass merchandizing applications it is desirable to have a scanner with the aggressiveness of a counter or slot scanner but which does require that the scanner be mounted or disposed with its window on the counter where it may present a snagging hazard to bar coded items, e.g., garments on hangers or hooks, if they are dragged across the counter for scanning. In other applications, e.g., where bar coded items are packaged in such -a way as to require that they not be inverted, it is also desirable to provide an aggressive, fixed mount scanner to project the scanning pattern down toward the counter from above so that items can be scanned right-side-up.
Thus, the need also exists for a counter mounted scanner which can project an aggressive scanning pattern from the side or above to scan items brought into the pattern, yet which pattern is relatively confined to minimize counter space required to be clear of bar coded items.
Some commercially available scanners are arranged to be disposed or mounted to project a scanning pattern somewhat laterally to act as a xe2x80x9cprojection scannerxe2x80x9d. Examples of such scanners are the following: the xe2x80x9cFREEDOMxe2x80x9d scanner sold by Spectra Physics, the xe2x80x9c7852xe2x80x9d scanner sold by NCR, the xe2x80x9cOMNISCANxe2x80x9d scanner sold by Microvideo, and the xe2x80x9cSLIMSCANxe2x80x9d scanner sold by Fujitsu. While such scanners are generally suitable for their intended purposes they all suffer from one or more drawbacks, such as somewhat large housing and/or xe2x80x9cfootprintxe2x80x9d size, amount of counter space to be kept clear of bar coded items, somewhat restricted working range, inability to scan all types of bar codes omnidirectionally and lack of agressiveness of scan pattern.
Accordingly, it is a general object of this invention to overcome the disadvantages of the prior art.
It is a further object of this invention to provide an extremely compact, fixed mounted scanning unit which overcomes the disadvantages of the prior art.
It is still a further object of this invention to provide a fixed mounted scanning unit which is arranged to project a rich scanning pattern into a confined volume for scanning a bar coded item brought therein irrespective of the orientation of the bar code.
It is yet a further object of this invention to provide an extremely compact, fixed mounted scanning unit which is arranged to project a rich scanning pattern laterally or downward into a confined volume for scanning a bar coded item brought therein.
These and other objects of the instant invention are achieved by providing a laser scanning device arranged to be stationarily supported at a counter for projecting a scanning pattern adjacent the counter, e.g., in a generally laterally outward direction with respect to said counter, and into which pattern a code having portions of different reflectivity, e.g., a bar code, to be scanned is located. The scanning pattern comprises plural, e.g., five, groups of plural, e.g., four, parallel scan lines.
The device basically comprises a compact housing, laser beam generating means, laser beam sweeping means, light reflecting means, light collecting means, and a window having a longitudinal axis and a transverse axis. The longitudinal and transverse axes of the window define a plane through which the scanning pattern is projected. The scanning pattern is generally confined within a relatively narrow, yet diverging, volume, e.g., pyramid, cone, frustum, etc., centered about a projection axis which is substantially but not precisely perpendicular to the plane of the window. For example, the projection axis may be at any angle within the range of from a slight deviation from precise perpendicularity up to approximately thirty (30) degrees therefrom. The light reflecting means comprises plural, e.g., at least five (5), reflecting members, e.g., mirrors. The laser beam sweeping means, e.g., a polygonal member having four (4) reflective surfaces arranged to be rotated about a rotation axis, serves to sweep the laser beam across the reflecting members, whereupon each of the reflecting members produces a respective one of the groups of lines of the pattern.
In one preferred embodiment of the device there are five reflecting members. The first reflecting member is disposed on a first axis of the housing opposite the polygonal member and extends along an axis parallel to the transverse axis. The first reflecting mirror is arranged to reflect the laser beam swept thereacross directly out through the window to produce the first group of scan lines. The second and third reflecting members are disposed on opposite sides of the first axis and closely adjacent laterally of the polygonal member. The first axis is parallel to the longitudinal axis and perpendicular to the transverse axis. Each of the second and third members extends along a respective axis at a small acute angle, e.g., 8 degrees, to the first axis and is arranged to reflect the laser beam swept thereacross directly out through the window to produce respective ones of the second and third groups of scan lines. The fourth and fifth reflecting members are disposed on opposite sides of the central axis between the second and third reflecting members, respectively, and each extends along a respective axis at a substantial acute angle, e.g., 48 degrees, to the longitudinal axis. Each of the fourth and fifth reflecting members is arranged to reflect the laser beam swept thereacross directly out through the window to produce respective ones of the fourth and fifth groups of scan lines.
The light receiving means comprises light focussing means and transducer means. The transducer means is arranged to receive light reflected from the code which enters the window, is reflected by the reflecting members and the beam sweeping means, e.g., the reflecting surfaces of the polygon, and is focussed by the focussing means, to convert it into an electrical signal indicative of the code.
The light focussing means basically comprises a collecting mirror having a concave reflective surface arranged to receive light from the beam sweeping means, e.g., reflective surfaces of the polygon, and to direct it to a concentrating lens. The lens acts to further focus the light onto the transducer means.